I have a 2000 Monte Carlo SS 3.8 V6 engine I I am putting a new thermostat in I would like to know what is the thermostat housing bolts what are their sizes so I can get new ones and replace the ones that are there they look kind of rusty

 

I don't recall off hand, but you can upgrade the T-stat bolts and the upper/lower intake bolts all to stainless. I had this company match all that hardware and they now offer a full kit. Pretty inexpensive in my book!
https://alloyboltz.com/product/3-8l-...ngine-hex-kit/